A variety of wheelchair seat cushion systems which include a tray or a base structure and a cushion positioned thereon have been proposed. Although many of these systems have realized significant commercial success, generally they suffer from a number of user-related drawbacks. Initially, many existing systems are relatively heavy. This increased weight is particularly disadvantageous to the user when exiting the wheelchair and collapsing the same for transport (e.g., when entering an automobile), which obviously requires removal of the wheelchair seat cushion system for storage. A significant portion of the weight of these systems is the fluid-filled cushion which is utilized since the corresponding tray is not appropriately anatomically conforming to the user. As such, designers/manufacturers have used an overabundance of fluid for the cushion to compensate for this non-conformance.
The design of the wheelchair seat cushion system can also have an effect on user comfort. For instance, heat and moisture are inevitably generated through use of the system. In the event that the system is not effective in dissipating heat and/or moisture, user discomfort and the risk of bed sores can result. Moreover, the shape of the wheelchair seat cushion system has a significant effect on user comfort. As an example, in many systems there have been significant problems with hammocking which adversely affects user comfort. Hammocking is a condition which occurs when the user is in effect being supported by the upper ply of the cushion versus the fluid therein and which is due to inadequacies in the design of the system.
The shape of the system also affects the distribution of the forces of the user's weight over the system. If force distribution is relatively poor, which equates with high or concentrated pressures, the user is susceptible to pressure sores. As such, maximization of the interfacing area between the user and the wheelchair seat cushion system is desirable. Moreover, the existence of significant shear-like forces between the user and the system can of course also contribute to patient discomfort.
Based upon the foregoing, there is a continuing need for a wheelchair seat cushion system which addresses user maneuverability and comfort issues to a greater and more effective extent than existing systems.